revert vector bump to be in sync with the docker image

Author: razvan

stacks/_templates/vector-aggregator.yaml

@@ -4,7 +4,7 @@ name: vector
 repo:
   name: vector
   url: https://helm.vector.dev
-version: 0.51.0 # app version 0.54.0
+version: 0.49.0 # app version 0.52.0
 options:
   commonLabels:
     stackable.tech/vendor: Stackable